AVS 53rd International Symposium
    Electronic Materials and Processing Friday Sessions
       Session EM-FrM

Paper EM-FrM11
Dynamics of Molecular Quantum-Dot Cellular Automata Devices and Circuits

Friday, November 17, 2006, 11:20 am, Room 2001

Session: Molecular Electronics
Presenter: Y. Lu, University of Notre Dame
Authors: Y. Lu, University of Notre Dame
M. Liu, University of Notre Dame
C. Lent, University of Notre Dame
Correspondent: Click to Email
Quantum-dot cellular automata (QCA) provides a non-transistor alternative for the design of molecular electronics. Binary information is encoded in the charge configuration of molecular cells. Information is transported from cell to cell through the Coulomb interaction. Clocked control of molecular QCA can be accomplished by employing an applied clocking field which varies regularly in both space and time. This enables binary information to be transported across molecular arrays without electrons moving between molecules. Power gain restores signal energy lost to unavoidable dissipative processes. Here we study dynamic properties of molecular QCA devices including energy dissipation, operating frequency, and defect tolerance. We use detailed quantum chemistry results for molecules to construct simpler effective Hamiltonians for each QCA molecular cell. We then solve the equation of motion of the whole molecular device using a coherence vector formalism which includes both quantum effects and dissipative coupling to the environment. This enables us to characterize non-equilibrium and finite-temperature effects on switching behavior. We explore the structure-function relation in molecular QCA at two levels: that of the individual molecules and that of the circuit layout. The specific character of the inter-dot intra-molecular linker plays a crucial role in the dynamics of molecular switching, particularly near the maximum possible switching speeds. At the level of the circuit as a whole, a key challenge for all molecular electronics is handling defects due to the fundamental thermodynamic inability to control exactly the position and orientation of each single-molecule device. The QCA approach has the advantage of being inherently robust against disorder and can be made even more so by simply using wider wires to build in redundancy.